Tuned audio relay



Jan. 15, 1946. FISCHLER 2,392,981

TUNED AUDIO RELAY Filed March 16, 1942 Patented Jan. 15, 1946 UNITEDSTATES PATENT OFFICE TUNED AUDIO RELAY Paul Elliott Fischler, Kenmore,N. Y., assignor to Technical Alliance, Inc., Kenmore, N. Y., a Icorporation of New York Application March 16, 1942, Serial No. 434,872

1 Claim.

This invention relates to tuned audio relays and has for its object toprovide a device of this kind comprising an A. C. relay, which may betuned to operate at any selected audio-frequency.

A further object is to construct the relay, and particularly the coreand coil thereof whereby it will have a fixed inductance value, when ina parallel resonant or series resonant circuit.

A further object is to provide a relay wherein the pivoted soft ironarmature is attracted toward the core by the magnetic flux, when saidflux is at its greatest intensity across the open ends of the core,which occurs at resonant frequency.

A further object is to provide an expansion spring for forcing thearmature away from the core and adjusting means for the armature actingagainst the spring for varying the adjustment 1 of the armature.

A further object is to form the core from laminations, and to provide acoil around the core spaced from the poles thereof and the whole havinga fixed inductance value.

A further object is to control a low pressure operating switch by therockable armature.

With the above and other objects in view the invention resides in thecombination and arrangements of parts as hereinafter set forth, shown inthe drawing, described and claimed, it being understood that changes inthe precise embodiment of the invention may be made within the scope ofwhat is claimed without departing from the spirit of the invention.

In the drawing:

Fig. l is a view in elevation of the tuned audio relay.

Fig. 2 is a vertical transverse sectional View taken on line 2-4 of Fig.1.

Fig. 3 is a horizontal sectional view taken on line 3-3 of Fig. 1.

Fig. 4 is a side elevation of the armature showing the same partly insection.

Fig. 5 is a schematic view of the parallel resonant energizing circuit.

Fig. 6 is a View similar to Fig. 5, but showing a series resonantenergizing circuit.

Referring now more particularly to the drawing, the numeral I designatesthe base of the device, formed from insulating or non-magnetic material,as shown, and supported on the base i by means of screws 2 which extendthrough sleeves 3 is a laminated core 4.

The core 4 is preferably rectangular shaped as shown, and is providedwith a gap 5 forming spaced magnetic poles 6, between which the magneticflux flows for attracting the inner end I of the rockable armature 8 ina direction toward the poles. That portion of the armature 8, above thegap 5, is enlarged as shown so there is a wide surface above the fieldof magnetic flux. The armature 8 is rockably mounted on adjustableplvotscrews 9, and by means of said screws an accurate and delicatebearing and suspension is obtained.

Secured to the base member I is an outwardly extending, angular shapedbracket l0 having an adjusting screw ll threaded therein, said screwcooperating with the recess l2 in the armature arm 1, and interposedbetween the inner side of the arm 1 and within a cup l3 suitably securedon the base i, is an expansion spring it. The screw member II is readilyaccessible and it will be obvious that by adjusting the screw i I, thearm 1 01' the armature may be accurately adjusted in relation to thecore gap 5 and poles Ii for obtaining a fixed position relative to thegreatest ma netic flux across the magnetic gap 5, and as the magnet orcore is energized by the alternating current passing through the coill5, around the portion it of the laminated core, said armature will beattracted toward the poles 6 against and under the influence of theexpansion spring Hi. It

is to be understood that the coil l5 and core 4 assembly has a fixedinductance value. This inductance, together with the capacity IS in the0 parallel circuit, or 20 in the series circuit, will cause greatestflux across gap 5 between poles 6 to occur at the resonant frequency,and the tension of spring I 4 is adjusted to allow the armature 8 to beattracted to the poles B only at resonant frequency;

As the armature 8 is attracted toward the poles 6, the outer and 8acloses a circuit at I! through the medium of a low pressure operatedswitch i8. It will be noted, in Fig. 5, that a parallel circuit is shownhaving a condenser l9 across the relay inductance, and in Fig. 6 isshown a series circuit in which the condenser 20 is in series with therelay inductance.

The operation is as follows: When the current in coil l5 producessufllcient magnetic flux across the gap 5 from the poles Ii to overcomeinertia of armature 8 and adjusted tension of spring H, the armature isattracted to the poles 6 of the core, moving on the pivotal points 9.The opposite movement of the outer end of the armature l is employed toclose the low pressure operating switch at 3, and as long as the deviceis energized at resonant frequency, the contacts I! remain closed.

From the above it will be seen that the device provides an alternatingcurrent relay, which may be tuned or caused to operate at any selectedaudio-frequency. The coil l5, and the core 4, provide a fixed inductancevalue, shown at 4 and IS in Fig. 5 in the parallel resonant circuit, andat 4 and 15 in the series circuit. shown in Fig. 6. The proper values ofIS and 20 with their respective inductances 4 and I5 will cause thecircuits to be resonant at any desired audio frequency of the appliedalternating current. As greatest magnetic flux across the open ends ofcore will occur at resonance, and as the tension of spring l4 may bevaried by adjusting the screw H, the armature 8 will be attracted to thepoles 6 only at the resonant frequency.

The invention having been set forth what is claimed as new and usefulis:

A tuned audio relay comprising a base, an alternating currentelectromagnet supported by and spaced from the base, said electromagnetbeing rectangular shaped and having a flux gap intermediate the ends ofone side thereof, an alternating current coil of fixed inductance valueextending around the side of said magnet opposite the flux gap andequidistant from the flux gap, a rockable armature supported by the baseand having its pivotal point spaced outwardly from the end of the magnethaving the flux gap, one end 0! said armature extending over the fluxgap in spaced relation thereto and to the outer side of the magnetparallel thereto and terminating between the flux gap and the coil, anexpansion spring carried by the base and extending upwardly and engagingthe under side of the armature and normally forcing the same outwardlyfrom the flux gap and an adjusting screw above the armature end andengaging the upper side of the armature and limiting the expansiveaction of the spring.

PAUL ELLIOTT FISCHLER.

